Retrievable cementing plug



Feb. 16, 1954 E. L. CONDRA 2,669,305

RETRIEVABLE CEMENTING PLUG Filed NOV. 20, 1 951 Aft [4074. [mm 1. 604 024,

Patented Feb. 16, 1954 UNITED STATES PATENT OFFICE RETRIEVABLE QEMENTING PLUG Elmo L. Condra, Long Beach, Calif. Application November 20, 1951, Serial No. 257,239

4 Claims. (Cl. 166-12) This invention relates to a cementing plug, also known as a bridging plug, for usein oil wells, for the purpose of providing a bridge or obstruction within the pipe or casing, so that cement can be poured into the well above the plug, thus preventing the cement from dropping to the bottom of the pipe or casing.

An object of my invention is to provide a novel cementing plug which can be retrieved and removed from the well after the cement has been poured at the proper place in the pipe or casing. Heretofore, cement plugs or bridging plugs were formed of a material which could be broken up or drilled out by the drilling bit. This required considerable time and also necessitated the removal of metallic particles from the well. With my invention, the entire cementing plug can be removed from the well after the cement has been poured and forced into its desired position in the casing or pipe.

Another object of my invention is to provide a novel retrievable cementing plug of the character stated in which the wall engaging sleeve or packing cup is forced outwardly against the pipe or casing by a wedging surface, but the amount of outward pressure against the packing sleeve or cup is limited due to a limited motion of the wedging element.

Another object of my invention is to provide a novel means of opening a valve in the retrievable cementing plug, so that fluid can flow through the cementing plug after the cement is placed, thus equalizing the static pressure above and below the tool. This is accomplished before the tool is removed from the well.

A feature of my invention is to provide a novel retrievable cementing plug which is simple in construction and effective in operation.

Other objects, advantages and features of invention may appear from the accompanying drawing, the subjoined detailed description and the appended claims.

In the drawing:

Figure l is a side elevation of my retrievable cementing plug with the parts arranged as when the tool is being lowered into the well. v

Figure 2 is a side elevation of the same with parts broken away to show interior construction, the parts being arranged as when the tool has been set in the pipe or casing.

Figure 3 is a sectional view taken on line 3-3 of Figure 1.

Figure 4 is a sectional view taken on line 4-4 of Figure 2.

Referring more particularly to the drawing,

the numeral 5 indicates the usual casing or pipe, which is to be cemented, by pouring the cement onto the cementing plug which is immovably positioned in the casing, as will be further described.

The cementing plug 2 consists of a bottom tube 3, the upper end of which is formed with an outwardly tapered surface 4 on which the pipe engaging slips 5 are mounted. These slips rest on the flat faces of the tapered surface 4 in the usual and well known manner, and each of the slips are attached to a slip ring 6 by means of the links .5, all of which is usual and well known.

A sleeve 8 surrounds the tube 3, and a plurality of spring fingers 9 are secured to this sleeve, and engaging the inner Wall of the casing l. The slip ring 6 is attached to the upper end of the sleeve 8 substantially as shown. A nut It on the lower end of the tube 3 screws into the bottom of the sleeve 8 and these threads are rather coarse so that the nut I!) will readily unscrew out of the sleeve 8, as will be further described.

A fitting H screws into the upper end of the tube 3 above the tapered surface 4 and this fitting is provided with a shoulder l2 on the upper end thereof, on which an expandable cup or plug 13 is mounted. The cup I 3 is annular in construction and is adapted to be stretched outward ly so as to pack off against the inside of the casing I, as will be further described. The cup i3 is made of rubber or plastic and is attached to the shoulder 12 of the fitting H, by any of the well known methods of securing rubber to a metal member.

A metallic tubular head I4 is formed with an outwardly extending annular cam or bulge l5, and when the tool is being run into the well, the cam 15 is positioned immediately above the cup 13, as shown in Figure l. The head It is provided with J slots l6, which are engaged by suitable lugs or pipes I! on the drill pipe It, thus permitting the tool to be lowered into the well. A cage I9 is threaded into the lower end of the head [4 and a valve 20 normally rests on the seat 2| in the cage. A post 22 rises from the valve 20 and a head 23 on the upper end of this post can be engaged by a grab on a fishing tool for the purpose of unseating the valve 20, as will be further described.

A plurality of pins 24 project outwardly from the head I 4 and these pins each extend into a slot 25 which is formed in the wall of the fitting II. The purpose of these pins is to limit the longitudinal movement of the head It relative to the fitting II and the packing cup l3. Also well to the point at which it is to be fixed. The springs 9 are dragging against the casing l and consequently will tend to hold the sleeve 8 stationary. By rotating the drill pipe 18, the tube 3 can also be rotated to unscrew the nut ill. The drill pipe 18 can now be lowered, thus causing the tapered surfaces 4 to press the slips 5 outwardly against the casing i. The entire slip assembly is now held in the well against longitudinal movement. Further downward movement of the drill pipe i9 will press the annular bulge or cam i5 into the top of the cup 13, thus pressing the cup outwardly against the casing l and securely packing ofi the annular space between the head l4 and the easing. The pins 24 will bottom in the slots 25, thus limiting the downward movement of the cam i5 and preventing excessive outward pressure on the inside of the cup l3, The valve 20 is resting on its seat and consequently any liquid or cement or the like which is above the cementing plug will be prevented from dropping downwardly in the casing. The drill pipe i3 is now disengaged from the slot [6 and removed from the well. The usual cementing operation now continues above the cementing plug 2 in the usual manner. When the cementing job is completed and before the cement sets, a fishing tool is lowered in the well until it grips the tip 29 and the valve 20 is then unseated. Water or oirculating fluid can then pass downwardly through the hollow tube 3 and the static pressures are equalized above and below the plug 2. The plug is retrieved by again inserting the drill pipe causing the lugs H to re-engage the J slots 16, then by pulling upwardly, the cam is pulled out of the cup 13 and at the same time the tapered surfaces 4 move upwardly to retract the slips 5. The tool can now be pulled out of the well.

Having described my invention, I claim:

1. A retrievable cement plug operated on pipe and comprising a tube, wall engaging means on tube, a fitting mounted on the upper end of said tube, an annular packing cup mounted on said fitting, a tubular head slidably mountedin said fitting and extending through said packing cup, releaseable means on said tubular head to support the plug on the pipe, and a cam on said head engageable with the packing cup to press said cup outwardly, and a valve seated in said tubular head.

2. A retrievable cement plug operated on pipe and comprising a tube, wall engaging means on said tube, a fitting mounted on the upper end of said tube, an annular packing cup mounted on said fitting, a tubular head slidably mounted in said fitting and extending through said packing cup, releaseable means on said tubular head to support the plug on the pipe, and a cam on said head engageable with the packing cup to press said cup outwardly, a valve seated in said tubular head, and means on the valve, said means being engaged to raise andunseat said valve.

3. A retrievable cement plug operated on pipe and comprising a tube, wall engaging means on said tube, a fitting mounted on the upper end of said tube, an annular packing cup mounted on said fitting, a tubular head slidably mounted in said fitting and extending through said packing cup, releaseable means on said tubular head to support the plug on the pipe, and a cam on said head engageable with the packing cup to press said cup outwardly, said fitting having a vertical slot therein, and a pin on said tubular head extending into said slot, and a valve seated in said tubular head.

4. A retrievable cement plug operated on pipe and comprising a tube, wall engaging means on said tube, a fitting mounted on the upper end of said tube, an annular packing cup mounted on said fitting, a tubular head slidably mounted in said fitting and extending through said packing cup, releaseable means on said tubular head to support the plug on the pipe, and a cam on said head engageable with the packing cup to press said cup outwardly, said fitting having a vertical slot therein, and a pin on said tubular head extending into said slot, a valve seated in said tubular head, and means on the valve, said means being engaged to raise and unseat said valve.

ELMO L. CONDRA.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 859,304 Larken et al. July 9, 1907 880,213 Heeter Feb. 25, 1908 1,423,213 Heeter July 18, 1922 1,804,818 Spang May 12, 1931 2,160,804 Hall et a1 May 30, 1939 2,374,169 Boynton Apr. 24, 1945 

